The present invention relates to heat sink devices for use in electronic devices, preferably in portable electronic devices, wherein electronic components comprising a semiconductor device or the like are arranged within a housing, for dissipating the heat generated by the electronic components to outside the housing.
With portable electronic devices such as notebook personal computers, laptop personal computers and other portable computer devices, the central processing unit (CPU) and other electronic components comprising a semiconductor device generate heat, which needs to be dissipated to outside the housing.
For example, notebook personal computers generally comprise a thin housing having a keyboard, and a display unit free to open and close relative to the housing. Disposed inside the housing is a printed circuit board having a CPU mounted thereon.
The present applicant has already proposed a heat sink device for the CPU of the notebook personal computer described (see JP-A No. 122774/1998). The device comprises a horizontal metal base plate formed by two metal sheets bonded to each other under pressure and having a hollow portion formed between the two metal sheets, a working liquid being enclosed in the hollow portion to provide a heat pipe portion. The metal base plate is disposed within the housing, and the heat pipe portion has a heat receiving part for receiving the heat generated by the electronic component.
Such a heat sink device is so designed that the CPU or like heat-generating electronic component is held in contact with the heat receiving part of the heat pipe portion. The heat generated by the electronic component is transferred to the heat receiving part of the heat pipe portion, and the working liquid collecting in the heat receiving part of the heat pipe portion evaporates by being heated with the heat. The working liquid in the form of a gas thus produced flows through the heat pipe portion away from the heat receiving part, dissipating heat into the air inside the housing through the metal base plate. The heat given to the heated air within the housing is dissipated to outside the housing through the keyboard.
Remarkable progress has recently been made in the field of portable electronic devices to provide devices having an increased number of functions and adapted to a higher processing speed, with the result that CPUs and like semiconductor devices of increased output are in use which generate a greatly increased quantity of heat. The conventional heat sink devices are therefore no longer fully efficient in dissipating the heat to outside the housing.